Abstract: We present novel realizations of the transitive signature primitive introduced by Micali and Rivest, enlarging the set of assumptions on which this primitive can be based, and also providing performance improvements over existing schemes. More specifically, we propose new schemes based on factoring, the hardness of the one-more discrete logarithm problem, and gap Diffie-Hellman groups. All these schemes are proven transitively unforgeable under adaptive chosen-message attack. We also provide an answer to an open question raised by Micali and Rivest regarding the security of their RSA-based scheme, showing that it is transitively unforgeable under adaptive chosen-message attack assuming the security of RSA under one-more-inversion. We then present hash-based modifications of the RSA, factoring and gap Diffie-Hellman based schemes that eliminate the need for ``node certificates'' and thereby yield shorter signatures. These modifications remain provably secure under the same assumptions as the starting scheme, in the random oracle model.
Ref: IEEE Transactions on Information Theory, Vol. 51, No. 6, June 2005, pp. 2133-2151. The preliminary version of this paper was entitled Transitive Signatures based on Factoring and RSA and appeared in Advances in Cryptology - ASIACRYPT 2002 Proceedings, Lecture Notes in Computer Science Vol. 2501, Y. Zheng ed, Springer-Verlag, 2002. Full paper (slight revision of the journal version) available below.
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